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List:       vdsm-devel
Subject:    [vdsm] [Users] Is this "dd" operation harmful?
From:       danken () redhat ! com (Dan Kenigsberg)
Date:       2012-10-14 14:25:29
Message-ID: 20121014142529.GF20780 () redhat ! com
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On Sun, Oct 14, 2012 at 09:44:39PM +0800, Shu Ming wrote:
> 于 2012-10-14 5:15, Dan Kenigsberg:
> > On Thu, Oct 11, 2012 at 11:38:19PM +0800, Shu Ming wrote:
> >> After reading the code, every mailbox should be 4096 byte size.
> >> And the total mailbox size is host * 4096. Ony one host is here, so
> >> the total mailbox size here is 4096. why should the 'dd' operation
> >> read 1024000 byte which is 1000K byte much lager than 4096 here?
> > The controlling parameter is MAX_HOST_ID=250, not the number of current
> > cluster members.
> I am wondering if we can do some optimization here, like to read and
> write the block size linear to the current cluster members.

There is a big place for optimization (and testability), as I've
mentioned in a previous post.

We do not have a cluster membership algorithm; only Engine knows how many
host are currently in the cluster. This knowledge can be propagated to
the SPM, I do not see an imminent race in this, but I guess a couple of
problems lurk there.

Dan.

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